A wing for an aircraft having a fixed wing, a foldable wing tip portion rotatably attached to the fixed wing and an actuation unit for rotating the foldable wing tip portion relative to the fixed wing about a hinge axis is disclosed. The actuation unit includes a traction means for transmitting traction between the fixed wing and the foldable wing tip portion, a main wheel attached to the foldable wing tip portion and in contact with the traction means and a drive means for generating traction to be transmitted by the traction means. The actuation unit generates traction with the drive means in the traction means so that the foldable wing tip portion can be rotated relative to the fixed wing.